(AP) — At least four people have been treated at a hospital after a pileup on ice-slickened Interstate 80 in western Nebraska.

The Nebraska State Patrol says the accidents were reported about 2:25 a.m. Wednesday near Maxwell. The patrol says a westbound semitrailer jackknifed on a patch of black ice, blocking traffic. Another semitrailer, a car and a pickup towing a trailer soon piled into the jackknifed truck.

The patrol says four people were taken to Great Plains Regional Medical Center in North Platte for injuries that were not considered life-threatening.

The interstate was closed for about 2½ hours as wreckers cleared the roadway. Traffic was diverted to U.S. Highway 30.

Black ice appears black because the ice is transparent enough to let the pavement color show through.